Differential expression of TNF receptors (TNFRs) in the colon of Crohn's disease versus intestinal endometriosis animal models

Crohn's disease (CD) and intestinal endometriosis (IE) are inflammatory disorders that present with similar symptoms confusing diagnosis. TNF is known to play an important role in both conditions; however, whether there are differences in the expression of TNF and/or its receptors which could be used for diagnosis and/or targeted therapeutics is unknown. Aim To compare RNA and protein levels of TNF, TNFRI and TNFRII in animal models of CD and IE. Methods Colitis was induced by administration of trinitrobenzene sulfonic acid (TNBS; 30mg/50% ethanol ic) (controls: vehicle). Endometriosis was surgically induced by suturing uterine horn implants beside the small intestine mesentery (controls: sutures only). TNF and TNFR gene expression and protein levels were measured in colon by real‐time RT‐PCR and immunohistochemistry. Results TNF gene expression was significantly upregulated in the colon of both models compared to their respective controls, but markedly higher in CD (96.2‐fold vs IE 9.7‐fold). In IE rats, both TNFRI and RII expression was downregulated 2‐fold. In contrast, gene expression of both TNFRs was upregulated in CD rats (TNFRI 3.3‐fold; TNFRII 68.4‐fold). At the protein level, these changes translated into a similar upregulation of TNF in both models (~2‐fold), while TNFRI and TNFRII expression was 4.2 and 1.6‐fold higher in CD than IE. Conclusions This study presents evidence for a significantly different pattern of gene and protein expression of TNFRs that could discriminate between these inflammatory diseases of the colon. S06GM08239 & RR03050